Photographic exposure-meter.



' M. LUPTON, JR. PHOTOGRAFHIC EXPOSURE METER.

E APPLICATION fiLED NOV.28, 1914. 1,144,142.

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Application lel November 28, 191e. s eerie; No; weeen T all whom it may, concern: A

Be i vknownthat I, Betreuerin M. Lor

TON, Jr.,a citizen of the United States, and

resident of Jersey City,inthe county of ;Hudson' and State of New Jersey, have invented certain new and useful Improvements in Photographic Exposure-Meters, of wlueh the following is a'sp'eciication.

Without recourse to This invention relates to' that class of photographic exposure meters whereby the requisite period 'or periods of exposureof the plates or iilms under many and varying photographic conditions may be predetermined without chemical tests.l ln using such devices of prior construction. it has been necessary to refer to certain accompanying ltables and to compute therefrom the period Vor periods of exposure ltofbe plate orrplates with e. certain diaphragm or iaphragms.

It Ais the object of myinvention to provide a. compact, self-contained device .of simpleconstruction which-vv may be easily and quickly manipulated to indicate the 4requisite period or periods of exposure under prevailing photographic conditions, and this pxtraneous factor tables or lthe like.

With this end in View my invention comprises a series of superposed coaxial indicating members bearing coordinated scales of photographicvalues which when brought into predetermined proximity or registry, by relative rotation of the said members, indicate the period or periods of exposure to be given a particular plate or plates with any specific diaphragm or range of diaphragnrisy j for any subject-or subjects under various v light conditions, as will be hereinafter par ticularly described and claimed.

In the drawings-Figure 1 is a face View,

enlarged, of an exposure meter embodying my invention. Fig. 2 is a back lView thereof. Fig. 3 .is a transverse vertical section, as on the line 3-3 ofFig. 1. Fig. 4 is a face view of a modified form of the meter.

5 designatesa ring, preferably of metal,

1 approximating in diameter and in 4thickness an ordinary silver dollar and having its periphery similarly knurled ormilled. This lring is provided withan internal annular' iange 6 upon the upper and lower sides of which are seated two superposed disks 7 8 respectively,`which are Sn'llglyencircled by the inner wall of the ring. he lperipheral margins of the'disks f?, Sar'ushg with the given j to the is dished or secketed to receive a third disk 9., whose upper surface isush, er subst/en tlally so, with the enelrcling racial pei-tion 'proximate surfces of the ring, lor substaun ytiallyl so, and t e acefof the upper disk 'Z of the A7. `The three disks, in conjxmcn tien with-thering are Connected by a cene;I

' trel pivot which'is preferably in the form of a rivet or eyelet li), and hence the disks J and the ring are independently retta about acommon central axis. The stru ure thus described simulates the form and appearance. of a coin or medal, and it may (similarly thereto be conveniently carried in the pocket, or Vit may be attached to a lrey ring, chain, or the like.

The face of uw disk e is rovi-ded, anja cent its periphery, with a Time of day scale o, comprising a segmental series ci ra dial graduations, numbered, for example, from 1 to Grund 6 to 1l, as shown, to indiM cate the day light hours `The face of thev disk is also providediadjacent its peripheral edge, 'with a Kind (ii/light scale b com prising a second segmental series of radial graduations which are marked to indicate various kinds of light as,for example, from Bright sunlight to Very dull as shown.

The exposed marginal portion of the disk \7 vis provided with a Month scale c, comprising a segmental series of radial'graduations which are numbered to indicate groups of months having approximat ly corresponding actinic values of day lig l t, as, for example, 11l and 12; 2 land 10, andso on, as shown. The graduations of the Month scale are spaced correspondingly with those I 'leo o'radial 4g'raduations with'several owhich v the graduations of the Kind of light scale are in' alinement when the Tir're' of day scale is positioned with. respect to the Month scale.- lThe exposed marginal portion of said disk '2' is also provided, adjacent the Month scale, with a radial index or i pointer, d, the function of which will presently appear. I

The' exposed face of the rin 5 is provided with a Plate or film speed scale' e, ee1fnl prisingsa segmental series of radial "r Sie ,plates or lms, su Y posed that the proper1=one`1sm registry tidns'numbered consecutively with spaced numerals, as, for example, 1/24 to 2, 1n accordance y-vvith Athe speed y equivalents of ch numerals being -so diswith a predetermined [graduation of the lfactors to one of Whiclifgthe index mark d- -on the disk points when" the predetermined plate speed number is properly positioned `-in respect to the Light sc ale.-v A "se" those of thescale andthe remain mental portionof the exposed: reversesi eVv or lback ofthe rin A5 is provided with a Speed fa'ctor? sca e g, comprisinge ual radial spacesl consecutively numbered with. the speed vfactors 1 to 12 corresponding ero such back isfpro'vi 'edi with a Seconds exo ure scale k comprising a series f'radial graduations numbered je finsecutivelm say', for example', from l/lOOO Sekte indicate seconds,v and fractions thereof 4.for exposure ofthe plates. The outer side of the disk 8 is riwidedj.A adjacent its periphery', with a' ubjects scale i, comprising a series ofxgraduations, identied with photographic subjects of I different light and shaderequigrements such 35.

for example, as Indoor a ortigait, ha banks, &c., as shown.

he.n outer side of the disk' is also provided with a .Dia-

phragm scaley', comprising a. of

radial graduations successively identified with the size numbersof various aperture diaphragms or stops ranging from smallest to present instance -tvvo equivalent size numybers are 'printed in each graduation', as,.for

example, U. S. 1 and f4 &c., as shown.

The disposition .of the subjects on -the scale i, as respects lightand shade requirements, and the or'der lof 'the speed numbers of the diaphragme on the scale y' are such, in relation to each other, that when the proper speed factor has been ascertained as above described, and the disk 8 is turned to bringe specific subject tothe like factor on the scale g, Vthe Diaphragm and Secends exposure scales "are in'F lose relation to each other, andthe proximate'numbers of said latter scales indicatelthe various periods of exposure .required forwthe correlated diapl'iragms designated on the disk 8.

Poreferably instructions for operating the exposures iihe largest aperture. Inutile.,

above described is -brieiy Kas followvszilAssume the month 'be February; the time be 10 a. 1n., the light'v be dull, and the speed of the lm be f 1/8: The disk 9 is'turned' on its axis until'the space denoted 10 of the 1 Time of day scale a is opposite the.

donethe ,index d on the disk 7 pointsto. j the speed factor 7 of the'scale f on the ring. 'The device is then inverted and the likeQs'peed factor observed on the scale g ,of the ring. Assume nonT that the subject be Light foreground, the 'disk S'is turned until the designation Light foreground ofthe scale c' thereon is opposite the ascer tained speed. factoren the scale g, whereupon by reference tothe Seconds ex- .posuref scale on the ring and the Diaphpagm scale,' on the disk 8 the various for particular diapliragms or apertures will be apparent, that is, for ex,-

ample, with a' diaphragm U, S, 4 or. f8 the speedwill be 1/35 second'.

From the foregoing it will' be; seentlatf i `given the speed equivaIentof-the late or .op "film to be used, the correct p erio of "ein,

posure (withim, certain time limitsof they i V dayk for alynno spending diaphragme or stops, can be ai of the year during' asyt flight)4 or varie'y of exposures withicorrel readily ascertained by merely turning the' several members ofthe device to their proper positions relative to'each other in.l

the sequence described.' It will also be seen' .d

"that these. exposures take into consideration :not only the speed of the' plate on film, but also` the month ofthe year with the consequent variation of the actinic .value of the rays of the sun,` the time of' day (for the same. reason,) the condition of the atmosphere as`respects its effect oirthe passage of the full power of the sunsj light, and the nature or condition of the object or sceneto be photographed depending upon the quantity of light it is able to reiiect as affectinggthe' photographic plate or film after concentration into a photographic image by means offthe camera lens, or other means. My invention thus provides an eicient photographic exposure meter, the

use of which requires no computing and no reference to' extraneous factor tables.'

My improved meter may be, made of metal or any other suitable material, or a combi# 12 `'nation of' several different materials, that device are printed thereon, part of such inffisfthe ring and disks may becomposed of metal and have inserted .therein celluloidy structions appearing on the .face disk 9 and thev remainder' on the backv disk 8, as illustrated.

The operation of the form of the device plates or disks with'pinted characters.' 'The device is, however, preferably madeentirely of metal with raised characters produced by means of dies or castings and the edges and bearing surfaces of the parts machine finished.

In a meterembodying my invention adapted to be used in connection with plates or lilms of a particular speed, one of the f disks may be omitted, thus further facilitating the procuring of. the periods of exposure.

and corresponding diaphragme or apertures. Such'a modified form of the device is illustrated in Fig. 4, by reference to which it will be observed that the disk 7 is omitted, that the Film or plate speed scale is absent from the face of the ring, and that'the latter bears the Month scale c and a Speed factor scale f arranged to accord with thepspeed equivalent of a Jparticular plate or film. In the present illustration the meter is adapted to' use with a 1/6 plate,

the several scales being 'so cordinated that when the disk 7 is turned to set a certain hour of the Time of day scale a in proper proximity to acharacter denoting a particular month on the Month scale, the varions. kinds of lightindicated on the scale "b -point to the proper factors on the Speed .ing groups of months; and a lower member movable relativelyA thereto on said body bearing two scales whereof *one indicates various photographic subjects and the'othcr denotes various diaphragms or stops. 7

2. A photographic exposure scale comprising a body having thereon three (zo-axial disks, two of which are super-posed on the upper side of the body and the other of'5a which Vis on" the underside of the body, the

upper surface of said body bearing-two scales whereof one indicates the various speed equivalents-of films or plates and thea-5v other indicates speed factors, and the lowerf'f55 surface of said body bearing two scales whereof-one indicates speed factors corresponding with those Aon the upper surface and whereof the other indicates seconds and fractions of seconds, one of said upper disks sa bearing a scale indicating the time of day and also a scale indicating variable light conditions, and the other of said upper disks bearing a scale indicating' groups of months and having also an index in operative relation to the proximate speed factors on the upper surface of the body, and the lower disk bearing two scales whereof one indicates various photographic subjects and the other denotes various diaphragms or stops.

LA photographic exposure meter coinprising an internally Hanged ring, and superposed disks seated` in said ring having a coinmonaxis of rotation, the `upper surface of said ring bearing a scaleI indicating,- speed factors and the lower surface of said ring bearing two scales whereof one indicates speed factors correspondmg with those on the upper surface and whereof the other indicates seconds and fractions -of seconds,

one of said disks bearing thereon adjacent the upper surface of the ring a scale indicating variable light. conditions and also a scale indicating thetime of day, said latter scale being cordinated with a suitablydisposed scale indicating groups of months, andanother of said disks bearing thereon adjacent the lower surface of the ring two scales whereof one indicates various photographic subjects and the other denotes va 90 rions diaphragms or stops.

Signed at New York inthe county and State of New York this 20th day of Novembei' A. 11,1914.

BENJAMIN M. LUPToN, .ne Witnesses: 1

B. CHANDLER SNEAD,

M. B. GOEWEY. 

